1. Field of the Invention
The present invention relates to a chemical mechanical polishing apparatus and, more particularly, to a chemical mechanical polishing apparatus capable of improving polishing uniformity.
2. Discussion of Related Art
A polishing method that has been used in an existing chemical mechanical polishing (CMP) equipment is a method of attaching polyurethane pad to a circular table made with rigid metal or ceramic and polishing the wafer while supplying the slurry on the pad. In this method, the polishing speed and uniformity are controlled depending on the speed of a platen to which the pad is attached, the speed of a head to which a wafer is attached, and the pressure applied to the rear of the wafer. Of them, in order to improve polishing uniformity, a multi-zone pressure method in which the pressure applied to the rear of the wafer is partially differentiated is used in chemical mechanical polishing.
Even with such advancement in the equipments, however, since it is difficult to fundamentally cope with irregularity problem of polishing at the edge of the wafer and a warpage problem, there may be a problem that polishing residue is left after the chemical mechanical polishing process, or one can""t control polishing rate.
The present invention is contrived to solve the aforementioned problems. The present invention is directed to provide a chemical mechanical polishing apparatus capable of obtaining a uniform polishing characteristic by controlling the degree of polishing depending on regions of a wafer, in such a manner that a plurality of support poles whose heights/locations can be controlled/moved are installed on a circular rotary table, a platen for polishing the surface of a wafer are divided into given shapes and are then attached to the plurality of the support poles, respectively, and a chemical mechanical polishing process is performed in a state the platens are assembled to have a desired shape by moving the support poles or the pressure applied to the wafer is controlled every region by controlling the height of the support poles.
According to one aspect of the present invention for achieving the object, there is provided a chemical mechanical polishing apparatus, including a circular rotary table, a driving shaft for rotating the circular rotary table, a plurality of support poles installed on the circular rotary table, wherein the support poles can be controlled in height and moved horizontally by sliding, and platen pieces each attached to the plurality of the support poles, wherein a platen of a new shape is assembled by horizontally moving the support poles or the pressure applied to a wafer is controlled every region by controlling the height of the support pole.
In the above, the support pole may have a hollow support rod for blowing off the slurry from its inner space. Further, an exhaust port for blowing off the slurry through the space between the platen pieces from the exhaust port may be installed at the circular rotary table between the support poles.
The platen pieces may include pieces of the platen that are divided in a checker pattern. The platen pieces may also include pieces that are divided into edges of a given width and a quadrilateral central portion in the platen. Meanwhile, different platen pieces may be attached to the central portion and the edge of the circular rotary table to control a polishing characteristic every region.
A pad in which a groove is formed at the interface between the platen pieces is attached to the platen piece. At this time, the pad may include an abrasive-embedded pad.